KR100247881B1 - Process for the preparation of urethane groups-containing polyurea elastomers - Google Patents

Abstract

The invention essentially consists of (a) diphenylmethane-based polyisocyanates and (b) isocyanate prepolymers (A) based on polyether polyols with a maximum hydroxyl functionality of 2.4, optionally with adjuvant and additive (d). Reactive component (B) consisting of aromatic alkyl-substituted diamines, which is characterized in that it relates to a method for producing an optionally foamed elastic molded article by reaction injection molding technology in a closed mold.

Description

[Name of invention]

Method for producing polyurea elastomer containing urethane group

Detailed description of the invention

The present invention utilizes a reaction injection molding technique to produce urethane group oils based on diphenylmethane-based polyisocyanates or polyisocyanate mixtures, relatively high molecular weight polyhydroxyl compounds and alkyl substituted aromatic diamines. It relates to a novel method of making polyurea elastomers.

A process for producing urethane group-containing polyurea elastomers based on diphenylmethane-based polyisocyanates or polyisocyanate mixtures, relatively high molecular weight polyhydroxyl compounds and alkyl substituted aromatic diamines using a reaction injection molding technique, A long-shot process is described in US Pat. No. 4,218,543, which describes. In this method, the polyisocyanate component is mixed with the compound as well as the additive containing an isocyanate reactive group. This method requires the use of a catalyst for the reaction between isocyanate groups and hydroxyl groups.

A relatively high molecular weight polyol component (b) and a polyisocyanate component (a) were obtained from JP 3,827,595 (which corresponds to US patent application Ser. No. 07 / 386,084, filed on July 28, 1989). After substantially complete preliminary reaction, the resulting isocyanate semiprepolymer is reacted with the diamine component, thereby producing a particularly large and different volume stream (large volume of isocyanate semi-polymer, small volume of diamine, compared to the one-shot method). Components), it is known that they have a number of significant advantages in terms of mechanical and thermomechanical properties such as dimensional stability under heating.

However, the inventors of JP 3,827,595 clearly point out that they can successfully produce higher elastomers only when the average hydroxyl functionality of the relatively high molecular weight polyhydroxyl component (b) is at least 2.5. .

Although the method according to JP 3,827,595, which is incorporated herein by reference, enables the production of elastomeric molded articles having a high level of mechanical properties, this method requires the use of branched polyhydroxyl compounds (b). The disadvantage is that the viscosity of the isocyanate semi-polymers is relatively high, which in many cases makes it difficult or impossible to fill large or complex molds, especially when inorganic reinforcing materials are used.

U.S. Patent 4,297,444 describes a process for producing polyurethane molded articles by reaction injection molding techniques using organic polyisocyanates, relatively high molecular weight polyhydroxyl compounds and low molecular weight chain lengthening agents. have. In a preferred embodiment, all of the relatively high molecular weight polyhydroxyl components are first reacted with the polyisocyanate component to produce an isocyanate semi-superpolymer, although this prior art system also employs a diamine component consisting of alkyl substituted aromatic diamines. It is not mentioned that it can be treated with or that any benefit can be obtained from this process. Although aromatic diamines are mentioned of suitable chain length extenders, their use is no longer discussed. In fact, the chain extender mentioned as preferred is a simple diol such as ethylene glycol or 1,4-butanediol. Only ethylene glycol is used in the examples. Thus, the possibility that a reactive system consisting of a stream of large volumes of isocyanate semi-polymers and a stream of small volumes of highly reactive diamines can be processed by the reaction injection molding technique cannot be deduced from the teachings of this document. .

German Patent Publication No. 1,240,654 does not contain monomers based on polyisocyanates other than the type to be used according to the invention, ie alkyl substituted diamines using true isocyanate prepolymers and difunctional polyhydroxyl compounds. And, preferably, in the presence of a solvent, a method of reacting with a conventional prepolymer process that does not utilize the principles of reaction injection molding techniques is described.

Published European Patent Application No. 0,075,130 describes a method analogous to that described in US Pat. No. 4,218,543, using certain prepolymers. However, this document generally describes the use of a significant amount of high molecular weight polyols on the B side.

The process according to the invention uses the reaction injection molding technique, even when using a relatively high molecular weight polyhydroxyl compound (b) having an average hydroxyl functionality of 1.9 to 2.4, the level of mechanical properties by the semi-superpolymer process described above. It is based on the surprising invention that this highly elastomeric molded article can be obtained. The method is particularly characterized by the following benefits:

(1) The viscosity of the semi-superpolymer obtained from the starting component is significantly reduced even when the other parameters are substantially the same. In this way, the semi-initial polymers used according to the invention based on polyetherdiols having an isocyanate content of 11.5% and an OH number of 56 have a maximum viscosity of 3000 mPa · s at 25 ° C., whereas 11.5% and a similar semi-initial polymer according to JP 3,827,595, based on OH value 56 other similar polyethertriols, has a viscosity at 25 ° C. of at least 4500 mPa · s.

(2) According to the invention, it is possible to use diphenylmethane-based polyisocyanate mixtures of higher functionality as polyisocyanate components and hence in many cases much less costly.

(3) The use of the method according to the invention produces molded articles with relatively improved release properties.

(4) The hardness (Shore D) increases faster as a result of the method of the present invention.

(5) When using a polypropylene oxide polyether having a hydroxyl value of 28 or more (which is very easily possible according to the present invention), a transparent molded article can be produced. More specifically, the present invention relates to a polyisocyanate component (a) consisting essentially of one or more polyisocyanates or polyisocyanate mixtures of diphenylmethane series, optionally liquefied by chemical modification, with an average molecular weight of 1000 to 6000 and an average of Isocyanate semi-superpolymers having a hydroxyl functionality of 2.4 or less and consisting essentially of one or more polyether polyols (b), which may contain dispersed organic fillers, with a NCO / OH equivalent ratio of at least 3.2: 1 Step (1) of forming (A) and at least one ortho to the semi-superpolymer (A), essentially the polyol component (b), the amino group, using the reaction injection molding technique in a closed mold Aromatic diamines (c) with alkyl substituents at positions and optionally isocyanates known from polyurethane chemistry Reacting component (B) consisting essentially of the whey reactive adjuvant and additive (d) with an isocyanate index of 70 to 130 (2), wherein the polyol component (b) of The amount is at least 90% by weight of the total amount of the polyol component used in the two reaction steps described above. .

In the first reaction step of the process, at least 90% of component (b) is reacted with the total amount of component (a) and then this isocyanate group and component (B) of component (A) in a closed mold in the second reaction step. The reaction is carried out with component (B) using a reaction injection molding technique under the conditions of maintaining an isocyanate index of 70 to 130 based on the isocyanate reactive group. Component (B) consists essentially of 0 to 10% of component (b), component (c) and optionally used isocyanate reactive single component. In addition, non-isocyanate reactive aids and additives (d) can be added to component (A) and / or component (B). This method is characterized in that component (b) has an average hydroxyl functionality of 2.4 or less.

The term “diphenylmethane series polyisocyanate” is a general term which refers to all polyisocyanates obtainable from the phosgenation of aniline / formaldehyde condensates and present as a mixture in this phosgenation product. The term “diphenylmethane series polyisocyanate mixture” refers to a specific mixture of diphenylmethane series polyisocyanates, ie, the above-described phosgenation products, such mixtures which are separated by distillation to obtain distillate or distillation residue. Mixtures, and particular mixtures of diphenylmethane series polyisocyanates.

The term “isocyanate semi-polymer” refers to polyisocyanates of the type used as component (a) according to the invention and to equivalents thereof in the form of relatively high molecular weight polyhydroxyl compounds of the type used as component (b) according to the present invention. Means the reaction product. Components (a) and (b) are isocyanates in quantitative ratios corresponding to NCO / OH equivalent ratios, 3.2: 1 to 19: 1, preferably 4: 1 to 10: 1, most preferably 5: 1 to 7: 1. Used for the preparation of semi-superpolymers (ie component (A)). In addition, in the context of the present invention, the properties and quantitative ratios of components (a) and (b) have a viscosity of semi-superpolymer (A) of 3000 mPa · s or less, preferably 1000 to 2600 mPa · s, at 25 ° C., and isocyanate The content is preferably selected to be 8-15% by weight, preferably 10-14% by weight.

“Isocyanate index” means the quotient of 100 divided by the quotient of the number of isocyanate groups divided by the number of isocyanate reactive groups.

In the process according to the invention, diphenylmethane series polyisocyanates can be used as starting component (a), optionally in modified form. Chemical modification is a chemical reaction that liquefies solid polyisocyanates, especially 4,4'-diisocyanatodiphenylmethane.

Typical examples of suitable polyisocyanates (a) include 4,4'-diisocyanatodiphenylmethane and mixtures thereof with 2,2'-, in particular 2,4, '-diisocyanatodiphenylmethane; Mixtures of these diisocyanatodiphenylmethane isomers with their higher homologs obtained by phosgenation of aniline / formaldehyde condensates; Modified diisocyanates and / or polyisocyanates obtained by partial carbodiimidation of the isocyanate groups of the above-mentioned diisocyanates and / or polyisocyanates; And mixtures of such polyisocyanates.

Aliphatic polyhydroxyl compounds having a molecular weight range of 62 to 700 in the above-mentioned diisocyanate and / or polyisocyanate and their equivalents up to the equivalent, for example ethylene glycol, trimethylolpropane, propylene glycol, dipropylene glycol or the foregoing Up to 30% by weight of urethane group-containing reaction product with polypropylene glycol in the molecular weight range (based on component (a)), preferably 20% by weight or less, may optionally be used for semi-initial polymerization. .

The polyol component (b) has an average molecular weight of 1000 to 6000, preferably 1500 to 3000, most preferably 1700 to 2500, and an average hydroxyl functionality of 1.9 to 2.4, most preferably calculated from hydroxyl group content and hydroxyl functionality. Preferably 1.9 to 2.1. The polyols of component (b) are most preferably polyetherdiols obtainable by known reactions of alkoxylation of bifunctional starter molecules such as water, ethylene glycol or propylene glycol, Also suitable are all polyether polyols or mixtures of polyether polyols which are suitable for definition. It is also possible to use organic fillers in dispersed form containing polyether polyols. Such dispersed fillers are, for example, vinyl polymers obtained by polymerizing acrylonitrile and styrene in polyether polyols as reaction medium [see US Pat. Nos. 3,385,351, 3,304,273, 3,523,093 and 3,110,695 and Federal Patent No. 1,152,536], or polyurea or polyhydrazide obtainable from organic diisocyanates and amines, diamines or polyamines or hydrazines by polyaddition reactions in polyether polyols as reaction media [Refer to German Federal Patents 1,260,142 and 2,423,984, 2,513,815, 2,550,833, 2,550,862, 2,633,293 or 2,550,769.

For polyether polyol alkoxylation, it is prepared in a known manner by alkoxylation of suitable starting molecules or mixtures of suitable starting molecules, in particular using propylene oxide and optionally also ethylene oxide. Examples of suitable starting molecules are water, ethylene glycol, propylene glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol, sugarcane sugar and mixtures thereof. The functionality of the starting molecule and the average functionality of the mixture of starting molecules should be suitable for the above conditions with regard to hydroxyl functionality.

The preparation of the polyether polyols (b) by alkoxylation of suitable starting molecules is carried out using propylene oxide as the alkylene oxide, in which case the hydroxyl groups are mostly secondary hydroxyl groups.

Component (c) is a diamine having an exclusively aromaticly bonded primary amino group and having at least one alkyl substituent at the ortho position relative to the amino group, in particular at least one alkyl substituent at the ortho position relative to the first amino group And a diamine having two alkyl substituents each having 1 to 4, preferably 1 to 3, carbon atoms in the ortho position relative to the second amino group. Particular preference is given to having ethyl, n-propyl and / or isopropyl substituents at one or more ortho positions for the amano groups, and optionally having methyl substituents at other ortho positions for the amino groups. Examples of such diamines or preferred diamines include 2,4-diaminomesitylene; 1,3,5-triethyl-2,4-diaminobenzene; 1,3,5-triisopropyl-2,4-diaminobenzene; Commercially available mixtures of 1-methyl-3,5-diethyl-2,4-diaminobenzene and 1-methyl-3,5-diethyl-2,6-diaminobenzene; And 3,5,3 ', 5'-tetraisopropyl-4,4'-diaminodiphenylmethane.

Mixtures of such diamines can also be used as component (c). Particularly preferred components are 1-methyl-3,5-diethyl-2,4-diaminobenzene and mixtures thereof with 1-methyl-3,5-diethyl-2,6-diaminobenzene (DETDA) (c) )to be.

Adjuvants and additives (d) optionally used may be, for example, inorganic fillers, conductive fillers such as conductive carbon black, dyes, pigments, organic blowing agents and / or internal release agents. Such auxiliaries and additives are known and are described, for example, in EP 81,701. For example, glass fibers are preferred inorganic fillers, and zinc stearate is a preferred internal mold release agent as a mixture with bonded solubilizers (see, for example, JP 3,626,673 and 3,636,502 and US Pat. No. 4,519,965). . The solubilizers mentioned above for zinc stearate are often isocyanate-reactive compounds. In many cases, the adjuvant and additive (d) thus contain such isocyanate-reactive components. For example, aliphatic polyols having a molecular weight range of 62 to 1000 and which may contain no nitrogen or may contain tertiary amine nitrogen atoms may also be present as component (d). Thus, compounds containing isocyanate-reactive groups optionally present in component (d) optionally used are mainly (i) aliphatic polyols having a molecular weight range of 62 to 1000, optionally containing tertiary amine nitrogen atoms, (ii) two Aliphatic aminopolyethers having a molecular weight range of 200 to 3000, and (iii) mixtures of these compounds, having at least a primary amino group. When using compound (d) containing an isocyanate reactive group, these compounds form part of component (B). In addition, when the adjuvant and additive (d) are inert to the isocyanate addition reaction, they can be added to one or both of component (A) and component (B). The amount of isocyanate-reactive compound (d) optionally used may be 50 equivalents or less, preferably 20 equivalents or less, based on the amino group of component (c) in the case of isocyanate addition reaction.

In order to carry out the invention according to the invention, an isocyanate semi-initial polymer (A) is first prepared from a polyisocyanate (a) and at least 90%, preferably a total amount of the polyol component (b). This reaction is usually carried out at a temperature of 25 to 100 ° C. Various methods for the preparation of isocyanate semi-polymers can be used. For example, the total amount of the polyisocyanate component (a) is reacted with the total amount of the provided component (b) for the preparation of the isocyanate semi-superpolymer (A), or, alternatively, a portion of the polyisocyanate component (a) is first After reacting with the total amount of component (b) provided for the preparation of the semi-superpolymer, the reaction product thus obtained can be mixed with the remainder of the polyisocyanate component (a).

The isocyanate semi-initial polymer thus obtained constitutes component (A) for subsequent reaction.

In a second step of the process according to the invention, component (A) is reacted with component (B) using a reaction injection molding technique in a closed mold.

Component (B) consists essentially of auxiliaries and additives containing up to 10% of the polyol component (b), diamine component (c) and optionally used isocyanate reactive groups, which are not used for the preparation of the isocyanate semi- d).

As mentioned above, optionally used auxiliaries and additives containing isocyanate inert groups can be incorporated into one or both of component (A) and component (B) to perform the second step of the process.

In the second step of the process according to the invention, for example, the reaction injection molding technique (“RIM method”) described in the above cited reference is used. In this process, reactive components (A) and (B) are used in amounts such that the isocyanate index is 70 to 130, preferably 90 to 120, based on these two components.

The amount of reaction mixture introduced into the mold is calculated to yield shaped articles having a density of 0.8 to 1.4 g / cm ³ , preferably 1.0 to 1.3 g / cm ³ . Molded articles with a density of 0.8 to about 1.0 g / cm ³ are microbubble elastomers, which are not true foams having a visually observable foam structure. This means that the blowing agents used optionally act as flow improvers rather than as true blowing agents. Particularly molded articles having a density of at least 1.2 g / cm ³ are obtained when inorganic fillers are used.

The starting temperature of the reaction mixture of component (A) and component (B) introduced into the mold is generally 20 to 80 ° C, preferably 40 to 70 ° C. The temperature of the mold is generally 30 to 130 ° C, preferably 40 to 120 ° C, most preferably 90 to 110 ° C.

The molds used are generally of the type known in the art and are preferably made of aluminum or steel. The inner wall of the mold can be coated with known external release agents to improve the release properties.

The molded article can generally be removed from the mold after staying in the mold for 5 to 180 seconds. After releasing from the mold, it can be tempered for 30-120 minutes at a temperature of about 60-180 ° C.

Molded parts obtainable by the process according to the invention are particularly useful for flexible bodywork, for example front and rear bonnets, side panels, mudguards and side rails of vehicles. Are particularly suitable for the production of) or when there are no glass fibers, they can be used as run-flat tires (to assist driving when the tires are damaged).

In the examples below, all percentages are by weight unless otherwise indicated.

EXAMPLE

The formulations described in the examples below are prepared using reaction injection molding techniques.

Component (B) containing isocyanate semi-superpolymer [= component (A)] and diamine (c) is transferred to a high pressure meter and mixed vigorously in a force controlled mixing head, and then they are rapidly temperature controlled hot metal mold [ Its inner wall was covered with a commercially available soap-based external release agent called RTCW 2006 sold by Chem Trend.

Steel plate molds are designed to produce test plates with dimensions of 300x200x3mm.

The mold is filled from the long side via a restrictor bar gate.

Example 1

[Preparation of Semi-Initiator (A)]

Diphenyl containing 32.5% isocyanate content and 90% containing diisocyanatodiphenylmethane isomers (which also contain about 90% of 4,4′-diisocyanatodiphenylmethane) (the remainder being highly functional polyisocyanates) 92 kg of the methane series polyisocyanate mixture [component (a)] is reacted with 109.7 kg of polypropylene glycol [component (b)] having a molecular weight of 2000 at 80 ° C. for 2 hours. The isocyanate content of the final product is 12.4% and the viscosity is 2200 mPa · s at 25 ° C.

Example 2

[Preparation of Semi-Initiator (A)]

A mixture of 256 kg of 4,4′-diisocyanatodiphenylmethane and 64 kg of 4,4′-diisocyanatodiphenylmethane (which was modified by partial carbodiimidation of isocyanate groups, with an isocyanate content of 30%) [Component (a)] was prepared by OH-valent 28-day polyether diol (which was prepared by propoxylating propylene glycol and then ethoxylating the propoxylated product; PO: EO weight ratio = 87: 13) [component (b )] React with 446.8kg at 80 ℃ for 2 hours. The semi-initial polymer thus obtained had an isocyanate content of 12.3% and a viscosity at 25 ° C. of 1150 mPa · s.

Example 3

[Method according to the present invention]

100 parts by weight of the semi-initial polymer (A) [component (A)] from Example 1, 14.43 parts by weight of 1-methyl-3,5-diethyl-2,4-diaminobenzene and 1-methyl-3,5 -7.77 parts by weight of diethyl-2,6-diaminobenzene, 2.96 parts by weight of polyricinoleic acid ester having an OH value of 30, Jeffamine D 400 [manufactured by Texaco, difunctional aliphatic aminopolyether Molecular weight 400] 1.48 parts by weight, a mixture of 1.48 parts by weight of zinc stearate and 1.48 parts by weight of a polyether polyol having an OH value of 810 prepared by propoxylation of ethylene diamine [i.e., component (B)] with 29.6 parts by weight Reaction is carried out using molding techniques (volume ratio of stream-about 4: 1).

The temperature of the mold is 110 ° C, and the residence time in the mold is 30 seconds. Molded articles obtained under these conditions are easily removed from the mold and have a flawless appearance.

The following mechanical measurements are measured for test plates tempered at 120 ° C. and 160 ° C. for 30 minutes, respectively.

Example 4

[Method according to the present invention]

The method used in this example is the same as in Example 3, except that 20 parts by weight of glass fibers are added as a filler to the semi-superpolymer (A) prior to the reaction (stream volume ratio-about 4.5: 1)

¹⁾ L = longitudinal direction, Q = transverse direction

^{2) The} SAG test is carried out at 160 ° C. for 60 minutes.

Example 5

100 parts by weight of isocyanate semi-initial polymer (A) [component (A)] from Example 2 14.43 parts by weight of 1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5 -7.77 parts by weight of diethyl-2,6-diaminobenzene, 2.96 parts by weight of polyricinoleic acid ester from Example 3, 1.48 parts by weight of zephamine D 400, 1.48 parts by weight of zinc stearate and OH from Example 3 1.48 parts by weight of a mixture of polyether polyols having a value of 810 [component (B)] and 29.6 parts by weight are reacted using the RIM method (stream volume ratio-about 3.4: 1).

The confusion of the mold is 110 ° C, and the residence time in the mold is 75 seconds. Molds obtained under these conditions have excellent release properties and have a flawless appearance.

The following mechanical properties are measured for test plates tempered at 120 ° C. and 160 ° C. for 30 minutes.

Example 6

[Influence of Functional Value of Component (b) on Viscosity of Semi-Initiator (A)]

The viscosity (at 25 ° C.) of the isocyanate semi-initial polymers (A) having isocyanate content of 11.5%, 12.5% and 13.5%, respectively, is shown in the table below. The polyisocyanate component (a) from Example 1 and polypropylene glycol having an OH value of 56 (functionality = 2) or propoxylated trimethylolpropane having a OH value of 56 (functionality = 3) were all prepared to prepare isocyanate prepolymers. Use it when. From this comparison it was found that the viscosity increased significantly due to the increase in the functionality of component (b).

TABLE 1

Although described in detail above for the purpose of illustrating the invention, it is to be understood that such techniques are for illustrative purposes only and do not depart from the scope and spirit of the invention except as may be limited by the claims of the present application. It should be understood that those skilled in the art can make modifications to the present invention.

Claims (10)

A polyisocyanate component (a) consisting of at least one polyisocyanate or a mixture of polyisocyanates of the diphenylmethane series and an average molecular weight of 1000 to 6000, a polyol consisting of at least 2.4 polyether polyols with an average hydroxyl functionality of 2.4 or less Reacting component (b) with an NCO / OH equivalence ratio of at least 3.2: 1 to form an isocyanate semi-initial polymer (A) having an isocyanate content of 8-15% by weight and a viscosity of 3000 mPa · s / 25 ° C. or less and sealing The alkyl substituent at one or more ortho positions relative to the semi-initial polymer (A) of step (1) and the total amount of the polyol component (b) and the amino group in the mold, using reaction injection molding technology in step (1) Reacting component (B) consisting of aromatic diamine (c) with an isocyanate index of from 70 to 130 (2), wherein Wherein the amount of polyol component (b) used to prepare the polymer is at least 90% by weight of the total amount of the polyol component used in the two reaction steps. The method of claim 1 wherein the polyisocyanate component contains at least one diphenylmethane series polyisocyanate liquefied by chemical modification. The process of claim 1 wherein component (b) contains a dispersed organic filler. The method of claim 1, wherein one or both of component (A) and component (B) include component (d) which is an adjuvant and an additive known from polyurethane chemistry. The method of claim 1 wherein component (B) contains each isocyanate reactive component of component (d). 6. The isocyanate-reactive component of component (d) according to claim 5, wherein the isocyanate-reactive component of component (d) has a tertiary amine nitrogen atom and an aliphatic polyol (1) having a molecular weight of 62 to 1000, at least two primary amino groups per molecule Selected from the group consisting of aliphatic amino polyethers (2) having a molecular weight of 200 to 3000 and mixtures thereof (3), wherein each isocyanate-reactive component is based on the amino group of component (c) in the case of isocyanate addition reaction Thus, the method is used in a total amount of 50 equivalent% or less. The method according to claim 1, wherein the polyol component (b) is a polyether polyol having an average molecular weight of 1500 to 3000 and an average hydroxyl functionality of 1.9 to 2.1. A process according to claim 1 wherein polyether polyols having secondary hydroxyl groups are used as component (b). The method according to claim 1, wherein the properties and quantitative ratios of component (a) and component (b) are 10 to 14% by weight and the viscosity thereof is 1000 to Method used to be 2600 mPa.s / 25 ° C or less. The composition of claim 1 wherein 1-methyl-3,5-diethyl-2,4-diaminobenzene or a mixture of this and 1-methyl-3,5-diethyl-2,6-diaminobenzene is a component. The method used as (c).